Remapping the Bixby button on Samsung Galaxy S10e (or any S9-S10 model) is possible through the Settings app.
Open the Settings application.
Locate and select the Advanced Features tab.
Press the Bixby key.
Enable "Double press" in the Bixby settings.
Select "Open App" from the menu.
Press the "Flashlight" icon, or select another available option.
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